The annual Hong Kong candlelight vigil to mark the 24th anniversary of the Tiananmen Square crackdown was brought to an abrupt end last night by heavy downpours and a power failure.

Adding to the drama, the key figure blamed for the June 4 incident was confirmed dead in Beijing last night.

Many people had braved the heavy rain, chanting slogans and turning Victoria Park into a sea of umbrellas. But an hour in, as weather conditions deteriorated, Lee Cheuk-yan, chairman of the main organiser, the Hong Kong Alliance In Support of Patriotic Movements in China, had to call an end to the vigil. It was supposed to run for two hours.

"I'm somewhat disappointed. It's really unfortunate. Once they announced the event was cancelled, the rain stopped," said one Hong Kong student participating in the vigil.

The organisers put the number of participants at 150,000, lower than their target of 180,000. Police reported the figure to be 54,000, down from 85,000 last year.

Video: Crowds pay tribute in Victoria Park

This came as the Hong Kong China News Agency reported that the disgraced former Beijing mayor Chen Xitong , widely believed to be a key figure behind the crackdown, died aged 84. The semi-official agency quoted unnamed sources as saying that Chen had passed away.

His son broke the news last night and sent texts to close friends of the family. A source who got the message said Chen died around 9am on Sunday at the China-Japan Friendship Hospital. Another friend said he was cremated on Monday.

Chen, whose name has long been associated with the bloody crackdown, was suffering from colon cancer. He was released from bail on medical parole in 2006 and died just three months before completing the jail sentence.

He was mayor of Beijing in 1989 and was later promoted to Beijing party secretary and made a Politburo member after the crackdown. Chen was sentenced to jail in 1998 for corruption. He tried to distance himself from the crackdown in his later years.

Chen's death added a dramatic touch to this year's June 4 anniversary, which has become a major annual event in Hong Kong, the only Chinese city that openly holds a large-scale memorial to mark the event.

The Hong Kong vigil was split this year, with some young people holding smaller vigils elsewhere, while conflict arose between a mainland victims' group and the main organiser.

Despite this, tens of thousands people from all walks of life last night gathered at Victoria Park to continue their fight for the crackdown to be redressed.

Some scheduled activities, including video messages from Li Wangling , sister of Li Wangyang , the mainland activist who died in suspicious circumstances last year, and Lu Yanjing, whose husband was killed in the Beijing crackdown 24 years ago, had to be cancelled.

In Beijing, at least 10 people from the victims' family group Tiananmen Mothers paid tribute to their loved ones in the Wanan graveyard.

This article appeared in the South China Morning Post print edition as: